U.S. patent application number 10/423179 was filed with the patent office on 2004-10-28 for implantable lead with intermediate insertion port for receiving a stiffening member.
Invention is credited to Sage, Shahn S..
Application Number | 20040215305 10/423179 |
Document ID | / |
Family ID | 33299050 |
Filed Date | 2004-10-28 |
United States Patent
Application |
20040215305 |
Kind Code |
A1 |
Sage, Shahn S. |
October 28, 2004 |
Implantable lead with intermediate insertion port for receiving a
stiffening member
Abstract
Implantable leads, lead assemblies, and methods for implanting
the leads into the human body. The lead can include numerous distal
electrical contacts for sensing and/or stimulation as well as
numerous proximal contacts for connecting to a lead extension
and/or an implantable pulse generator. The lead includes a stylet
lumen extending between a side-wall stylet entrance port and the
lead distal region. Some leads further include a stylet guide
disposed near the stylet opening for fluoroscopic visualization
and/or insuring proper insertion and distal advancement of the
stylet within the lead. In use, the stylet can be inserted through
the lead stylet port to stiffen only the distal portion of the
lead, and the distal portion of the lead inserted through an
introducer needle into the human body. The stiffened distal portion
of the lead can be short and easily controllable. Implantable leads
having an intermediate stylet insertion port find one use as
neurological stimulation leads for implantation within the
intrathecal spaces of the spinal column to manage pain. The short,
stiffened portion of lead allows for a longer total lead length
which can eliminate the need for lead extensions in some
applications.
Inventors: |
Sage, Shahn S.; (Andover,
MN) |
Correspondence
Address: |
INTELLECTUAL PROPERTY GROUP
FREDRIKSON & BYRON, P.A.
200 SOUTH SIXTH STREET
SUITE 4000
MINNEAPOLIS
MN
55402
US
|
Family ID: |
33299050 |
Appl. No.: |
10/423179 |
Filed: |
April 25, 2003 |
Current U.S.
Class: |
607/122 |
Current CPC
Class: |
A61N 1/0551 20130101;
A61N 1/0529 20130101; A61N 1/0558 20130101 |
Class at
Publication: |
607/122 |
International
Class: |
A61N 001/05 |
Claims
What is claimed is:
1. An implantable lead comprising: an elongate lead body comprising
a proximal region, a distal region, an intermediate region disposed
between the proximal and distal regions, and a sidewall; at least
one conductor disposed within the lead body and extending from the
proximal region to the distal region; at least one proximal contact
disposed in the lead body proximal region and in electrical contact
with the at least one conductor; at least one distal contact
disposed in the lead body distal region and in electrical contact
with the at least one conductor; a lumen disposed through the lead
body between the distal region and the intermediate region; and a
port providing access through the lead body sidewall to the lumen
in the intermediate region.
2. An implantable lead as in claim 1, wherein the at least one
proximal contact comprises a plurality of proximal contacts and
wherein the at least one distal contact comprises a plurality of
distal contacts, wherein the port is disposed between the innermost
of the proximal and distal contacts.
3. An implantable lead as in claim 1, further comprising a
radiopaque marker disposed near the port.
4. An implantable lead as in claim 3, wherein the marker includes a
radiopaque seal disposed at least partially in the port.
5. An implantable lead as in claim 1, further comprising a stylet
guide disposed about the port, the stylet guide including an
aperture therethrough for receiving the stylet.
6. An implantable lead as in claim 5, wherein the stylet guide
includes a stylet guide arm extending radially and distally into
the port for distally directing an inserted stylet.
7. An implantable lead as in claim 1, wherein the lead has an outer
diameter of less than about 1 millimeter and a total length of
between about 10 cm. and about 150 cm.
8. An implantable lead as in claim 1, wherein the lead has a
longitudinal axis and wherein the port is dimensioned and
configured such that a stiffening member inserted into the lead
from the intermediate region to the distal region lies at an angle
of less than about 40 degrees from the lead longitudinal axis near
the port.
9. An implantable lead comprising: an elongate lead body comprising
a proximal region, a distal region, and an intermediate region
disposed between the proximal and distal regions; means for
providing electrical continuity between the proximal and distal
regions; and means for reversibly stiffening the lead between the
intermediate and distal regions while not stiffening the lead
between the intermediate and proximal regions.
10. An implantable lead as in claim 9, wherein the means for
reversibly stiffening the lead comprises means for receiving a
stiffening member into the lead body for disposition between the
intermediate region and the distal region.
11. An implantable lead as in claim 10, wherein the means for
providing electrical continuity comprises a plurality of proximal
electrical contacts electrically coupled to a plurality of distal
electrical contacts, wherein the means for receiving a stiffening
member is disposed between the innermost of the proximal and distal
contacts.
12. An implantable lead as in claim 9, further comprising means for
radiopaquely marking the lead intermediate region
13. An implantable lead as in claim 10, further comprising means
for radiopaquely marking and sealing the means for receiving the
stiffening member.
14. An implantable lead as in claim 10, wherein the means for
receiving a stiffening member further comprises means for guiding
the stiffening member into the lead body.
15. An implantable lead as in claim 14, wherein the means for
guiding the stiffening member into the lead body includes means for
distally directing the stiffening member into the lead body.
16. An implantable lead as in claim 9, wherein the lead has an
outer diameter of less than about 1 millimeter and a total length
of between about 10 cm. and about 150 cm.
17. An implantable lead assembly comprising: an elongate stiffening
member having a proximal region and a distal region; an elongate
lead body comprising a proximal region, a distal region, an
intermediate region disposed between the proximal and distal
regions, and a sidewall; at least one conductor disposed within the
lead body and extending from the lead body proximal region to the
lead body distal region; at least one proximal contact disposed in
the lead body proximal region and in electrical contact with the at
least one conductor; at least one distal contact disposed in the
lead body distal region and in electrical contact with the at least
one conductor; a lumen disposed through the lead body between the
lead body distal region and the lead body intermediate region; and
a port providing access between the lead body sidewall and the
lumen in the lead body intermediate region, wherein the port and
lumen are dimensioned to slidably receive the elongate stiffening
member.
18. An implantable lead assembly as in claim 17, wherein the
stiffening member further comprises a handle secured to the
proximal region, wherein the handle includes a channel dimensioned
to receive and releasable grip the lead body.
19. A method for inserting an implantable lead into the human body,
the method comprising: providing an elongate stiffening member
having a proximal region and a distal region; providing an elongate
lead body comprising: a proximal region, a distal region, an
intermediate region disposed between the proximal and distal
regions, and a sidewall; at least one conductor disposed within the
lead body and extending from the lead body proximal region to the
lead body distal region; at least one proximal contact disposed in
the lead body proximal region and in electrical contact with the at
least one conductor; at least one distal contact disposed in the
lead body distal region and in electrical contact with the at least
one conductor; a lumen disposed through the lead body between the
lead body distal region and the lead body intermediate region; and
a port providing access between the lead body sidewall and the
lumen in the lead body intermediate region, wherein the port and
lumen are dimensioned to slidably receive the elongate stiffening
member; and inserting the lead distal region into the human body
while carrying the stiffening member at least partially within the
lumen between the port and the lead distal region.
20. A method for inserting an implantable lead into the human body
as in claim 19, further comprising inserting the stiffening member
into the lead through the lead port before inserting the lead
distal region into the human body.
21. A method for inserting an implantable lead into the human body
as in claim 20, further comprising providing an introducer needle
and inserting the introducer needle into the human body, wherein
the inserting implantable lead step includes inserting the lead
carrying the stiffening member into the introducer needle.
22. A method for inserting an implantable lead into the human body
as in claim 19, further comprising retracting the stiffening member
from the inserted lead distal region.
Description
FIELD OF THE INVENTION
[0001] The present invention is related generally to medical
devices. More specifically, the present invention is related to
implantable, electrical neurological leads.
BACKGROUND OF THE INVENTION
[0002] Implantable leads having externally exposed ring or band
electrodes can be used to both deliver electrical stimulation to
surrounding tissue and to sense electrical energy produced by the
surrounding tissue. Such leads are often implanted within the
epidural or intrathecal spaces of the spinal column, along
peripheral nerves, within the brain, and about the heart.
Electrical stimulation in the spinal cord has been shown to be
effective in relieving intractable pain in some patients. Such
electrical stimulation can reduce or eliminate the use of pain
relieving drugs.
[0003] A neurological stimulation lead is commonly used to deliver
the electrical signals. One such lead is formed of polymeric
material, for example, polyurethane or silicone. The lead can be
nominally 1 mm in outer diameter and about 20 cm in length. A
typical lead may have a series of electrodes formed as bands or
rings disposed in a spaced apart relationship in a lead distal
region. The distal region of the lead can later be introduced into
the spinal column. One such lead has eight electrodes in the distal
region, with each electrode having its own conductor extending the
length of the lead to a proximal lead region. The lead proximal
region can have a corresponding set of band or ring connectors or
terminals, one for each corresponding electrode in the distal
region. Each proximal region terminal can thus be connected to one
distal electrode in a typical configuration.
[0004] The terminals can be used to couple the proximal end of the
lead to a lead extension which can in turn be coupled to an
implantable pulse generator (IPG). The lead extension can provide
added length to extend the reach of the lead to a more distantly
placed IPG. In some embodiments, the lead extension is between
about 20 and 50 cm in length.
[0005] The lead typically has a lumen extending from the proximal
end through to the distal region, with the lumen being dimensioned
to accept a stiffening member or stylet. The lead, commonly formed
of a polymeric material and being very small in cross section, is
typically very floppy and not pushable. With a stylet or stiffening
member inserted, the lead gains the needed pushability, and can be
advanced into and up the spinal column to the desired location.
[0006] In use, a large gauge Toughy needle can be inserted into the
spinal column and into the spinal canal. The stylet is then
inserted into the lead, and the now stiffened lead advanced through
the needle and up into the spinal canal. When the distal region of
the lead is in the proper position, the stiffening member can be
removed and the introducing needle also removed, leaving the
proximal end of the lead protruding from the patient.
[0007] A small incision can then be made near the site of entry of
the lead, in order to direct the proximal end of the neurological
lead back into the body to be mated to a lead extension or to the
IPG. The proximal end of the lead extension is coupled to the
proximal end of the lead, and electrical continuity established.
The lead extension is used to extend the useful length of the lead
sufficient to reach the implanted IPG, which can be, for example,
20-50 cm distant. With the length increased by the extension, the
free end of the extension can be inserted into the incision and
into the body.
[0008] In one procedure, known as "tunneling", an elongate,
flexible metal device is used to form a tunnel or passageway under
the skin, for example, around the torso, to the site of the
implanted or soon to be implanted IPG. This tunneling procedure can
be used to form the passageway for the extension which is then
advanced through the passageway and to the IPG site.
[0009] The extension, while adding length, also adds complexity and
cost. It also adds yet another required step for the treating
physician to perform. Increasing the lead length to do away with
the need for the extension would be desirable. However, with
current leads, the stiffening member or stylet would likewise have
to be increased in length. While this is possible, a significantly
longer lead having a stiffening member within would be somewhat
unwieldy. For example, a 50 cm long stylet inserted within a 50 cm
long lead would be difficult for the treating physician to
maneuver. This aspect is significantly limiting, given that the
treatment site is the spinal cord, where care must be
exercised.
[0010] What would be desirable are neurological stimulating leads
which are sufficiently long so as to be able to do away with any
required extension. What would be advantageous are long
neurological leads providing distal stiffness and pushability
without being unwieldy for the treating physician. What would also
be beneficial are neurological leads which can be provided in a
variety of lengths all sharing a common stiffening member, not
requiring a different stiffening member to match each size
lead.
SUMMARY OF THE INVENTION
[0011] The present invention provides an implantable lead including
a proximal region, a distal region, an intermediate region disposed
between the proximal and distal regions, and a side wall. The lead
further includes at least one proximal contact and at least one
distal contact, electrically coupled to each other by a conductor.
The lead includes a lumen disposed through the lead body between
the distal region and the intermediate region and a stylet port
providing access between the lead body sidewall and the lumen in
the intermediate region. The stylet port and lumen can be adapted
to slidably receive a stiffening member or stylet through the port
and into the lead distal region. Some embodiments of the present
invention include an implantable lead assembly including the
implantable lead and a stylet adapted to be slidably received in
the implantable lead stylet port and stylet lumen.
[0012] Some implantable leads have a plurality of distal contacts
and a plurality of proximal contacts, with the stylet port disposed
between the innermost of the distal and the proximal contacts. Some
leads have a radiopaque marker disposed nearer the stylet port for
locating the stylet port under fluoroscopy. The marker can include
a radiopaque seal disposed at least partially in the stylet port.
Some leads include a stylet guide disposed about the stylet port,
the stylet guide including an aperture for receiving the stylet.
Some stylet guides include a stylet guide arm extending radially
and distally into the stylet port for distally directing an
inserted stylet. The stylet guide can be formed of, and/or plated
with, a radiopaque material such as gold or platinum.
[0013] In use, an implantable lead having the desired total length
and suitable characteristics is selected for implantation. The lead
preferably has a stylet lumen extending between the lead side wall
stylet port and the lead distal region. The length between the
stylet port and the end of the stylet lumen is preferably
dimensioned to receive the stylet, regardless of the total lead
length. An introducer needle can be advanced into the body near the
implantation site. The stiffening member or stylet can be inserted
into the lead stylet port and further distally into the lead to
stiffen the lead distal region. The stiffened lead can be inserted
through the lumen of the introducer needle and further distally
from the needle to the target site. The stylet can be retracted
from the lead, and the introducer needle retracted as well, leaving
the lead proximal region extending from the body. In some methods,
the lead proximal end is coupled to a lead extension before being
tunneled into the body to fully implant the lead.
[0014] The lead, lead assembly, and lead implantation methods allow
for implanting a variety of lead lengths while stiffening only the
lead distal portion. The lead portion disposed proximal of the
stylet port need not be stiffened and/or include a stylet lumen
within. This remaining lead proximal portion can be sufficiently
long to eliminate the need for a lead extension by not requiring
that the entire lead length accept a stylet to provide for
stiffening. A single length stylet may thus be used with a family
of leads, each having a different total length, but having a
similar length stylet lumen within.
DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a side view of an implantable lead having an
intermediate stylet insertion port and a stylet for insertion into
the port;
[0016] FIG. 2 is a fragmentary, longitudinal cross-sectional view
of a distal portion of the lead of FIG. 1;
[0017] FIG. 3 is a transverse, cross-sectional view taken through
3-3 of FIG. 2, showing a distal tri-lumen portion of the lead;
[0018] FIG. 4 is a perspective view of a stylet guide or marker
which can be positioned over the intermediate insertion port of a
lead;
[0019] FIG. 5 is a fragmentary, cutaway view of a lead intermediate
portion having the stylet marker of FIG. 4 guiding a stylet into
the intermediate insertion port;
[0020] FIG. 6 is a fragmentary, longitudinal, cross-sectional view
of the lead intermediate portion of FIG. 5, having a sealing filler
material sealing the intermediate insertion port;
[0021] FIG. 7 is a fragmentary, perspective view of an assembly
having a stylet handle adapted to grip a neurological lead; and
[0022] FIG. 8 is a transverse, cross-sectional view of the handle
of FIG. 7, having the lead held within the longitudinal
channel.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] FIG. 1 illustrates a neurological stimulation lead 20 having
a distal region 24, a proximal region 26, and an immediate region
28 disposed between the distal and proximal regions. In a preferred
embodiment, the intermediate region is defined to lie between the
innermost distal and proximal electrical contacts described below.
A stylet entrance or insertion part 42 may be seen in intermediate
region 28. Lead 20 can be formed of a body or shaft 34 extending
between a distal end 30 and a proximal end 32. Lead body 34 has an
exterior surface or tubular side wall 36. Lead body 34 is
preferably formed of a polymeric material, for example,
polyurethane or silicone.
[0024] Lead distal region 24 can include a number of electrodes 38
which can be disposed concentrically about lead body 34 in a
spaced-apart configuration. Electrodes 38 may also be described as
electrical contacts or contacts. Electrodes 38 are normally adapted
to be inserted into the human body, are externally exposed, and can
be used for neurological stimulation. One exemplary use of
electrodes 38 is the stimulation of the nerves within the spinal
cord. Proximal region 26 can include a number of connector bands or
connector rings 40 disposed in a spaced-apart configuration.
Connectors 40 may also be described as electrical contacts or
terminals, and are preferably also externally exposed. Electrodes
38 and connectors 40 may be formed of Platinum and/or Iridium.
Connectors 40 can be used for connecting lead 20 to a lead
extension to extend the effective length of the lead. In some uses,
connectors 40 may also be used to directly couple lead 22 to an
implantable pulse generator.
[0025] Electrodes 38 and connectors 40 can be coupled to each other
in a one-to-one arrangement. In some leads, the distal-most
electrode is coupled to the distal-most connector, the
second-to-distal-most electrode coupled to the
second-to-distal-most connector, and so forth. The electrodes and
connectors can be coupled through conductors extending between the
two. In some leads, the conductors are embedded within the lead
while in other leads, the conductors lie within lumens extending
the length of the lead. In some leads, the conductors are disposed
within lumens which are later backfilled to substantially fill the
lumens with a polymeric material.
[0026] FIG. 1 also illustrates a stylet 50. Stylet 50 includes
generally a shaft 56 extending between a distal tip 52 and a
proximal end or handle 54. Stylet 50 is typically dimensioned to be
slideably received within stylet entrance 42 and further within a
lumen extending distally from stylet entrance 42 toward distal
region 24.
[0027] Lead 20 can be varied in outer diameter and length to suit
the application for which it is intended. In some embodiments, lead
20 has a total length of between about 5 cm and about 100 cm. In
other embodiments, lead 20 has an outer diameter of less than about
1 mm and a total length of between about 10 cm and 150 cm. The lead
length between stylet entrance 42 and distal end 30 can vary as
well. In some embodiments, the distance from stylet entrance 42 to
distal end 30 is less than 50 cm, preferably less than 30 cm, and
most preferably less than about 20 cm. Stylet 50 preferably has a
length adapted to approximately match the length between stylet
entrance 42 and distal end 30. Stylet 50 preferably has a shaft
outer diameter of less than about 0.050 inches, more preferably
less than about 0.020 inches, and most preferably less than about
0.010 inches.
[0028] FIG. 2 illustrates a distal portion of lead 20 in
longitudinal cross-section. Lead 20 may be seen to have a flared
lumen portion 41 extending from stylet entrance or port 42 toward
distal region 24. A stylet lumen 43 may be seen to extend distally
from stylet opening 42. In the embodiment illustrated, stylet lumen
43 terminates proximal of lead distal end 30. In some leads, port
42 lies at an angle of between about 20 and 60 degrees from the
longitudinal axis of the lead. In one lead embodiment, port 42 lies
at an angle of about 30 degrees from the lead longitudinal axis. In
other embodiments, port 42 is dimensioned and configured such that
a stiffening member inserted into lead 20 to distal region 24 lies
at an angle of less than about 40 degrees, preferably about 30
degrees, from the lead longitudinal axis near port 42. Leads
preferably have a distal region wall thickness of at least about
0.004 inch. In some leads, a plug material can be disposed within
or about stylet port 42 in order to provide a seal between the lead
lumen or lumens and the body in which it is inserted. In some
leads, a silicone polymeric material carrying a radiopaque marker
material is used to plug stylet port 42. In one such plug material,
silicone carrying a barium oxide radiopaque material is used as the
plug material. The plug or seal material can be inserted into port
42 during manufacture. The stylet distal tip can be advanced
through the silicone sealing material to stiffen the lead, and can
later be retracted. In some embodiments, radiopaque marker bands
can be disposed near one or both sides of stylet port 42 in order
to better mark the stylet port for identification of the stylet
opening location under fluoroscopy, should surgical access to the
port later be required.
[0029] FIG. 3 illustrates a transverse cross-section taken through
a distal portion of lead 20. Lead 20 may be seen to have a
tri-lumen configuration in FIG. 3, having a first lumen 45, a
second lumen 47, and a third or stylet lumen 43. The tri-lumen
configuration can be used to provide lumens for conductors
extending between the electrodes and connectors, while separating
the conductors from the inserted stylet. The conductors may lie
within first and second lumens 45 and 47, leaving lumen 43 clear to
receive a stylet. In some leads, a mono-lumen configuration may be
found proximal of the stylet opening, where the stylet presence
need not be adapted for, leaving a larger cross-sectional area for
the conductors.
[0030] FIG. 4 illustrates a stylet guide or marker 60 for
augmenting and marking stylet entrance 42. Stylet guide 60 can be
used to both mark the stylet entrance and to aid in proper
insertion of the stylet into the lead. Stylet guide 60 may be seen
to have generally a distal end 66, a proximal end 68, a
substantially cylindrical body 62, an outer surface 64, and an
inner surface 70. Cylindrical body 62 may be seen to include a gap
72, an aperture 74, and a deflector arm 76 for properly directing a
stylet into the stylet lumen. Stylet guide 60 may be made from
sheet metal, for example, stainless steel. The sheet metal may be
stamped into the appropriate shape, with aperture 74 being formed
through body 62 and deflector arm 76 pushed downward from aperture
74. Stylet guide 60 may then be plated with a radiopaque marker
material, for example, gold or platinum.
[0031] FIG. 5 illustrates an intermediate portion of another
neurological lead 80, similar in many respects to lead 20 of FIG.
1, and sharing some identically numbered features. Lead 80 differs
in having a stylet port or opening 82 which is not flared. Lead 80
includes stylet guide or marker 60 of FIG. 4 disposed over and
about stylet opening 82. Stylet deflector arm 76 may be seen
guiding stylet shaft 56 distally into stylet lumen 43. First
conductor lumen 45 may also be seen, previously discussed with
respect to FIG. 3. As may be seen from inspection of FIG. 5,
deflector arm 76 extends radially inward and distally along stylet
guide aperture 74 to ensure that stylet shaft 56 can be inserted in
only the distal direction. Stylet guide 60 can also serve to
provide a large radiopaque marker easily visible under
fluoroscopy.
[0032] FIG. 6 further illustrates lead 80, having a seal or filler
material plug 84 disposed within stylet opening 82. Stylet guide 60
and deflector arm 76 may also be seen in FIG. 6. In some methods,
seal 84 is injected or placed after withdrawal of the stylet and
proper placement of the lead. In a preferred embodiment, seal 84 is
injected or otherwise placed within stylet opening 82 during
manufacture, with the stylet being inserted through the soft
pliable material.
[0033] FIG. 7 illustrates an assembly 100 including a stylet wire
or shaft 108 coupled to a stylet proximal handle 102 being inserted
into a neurological lead 104. Stylet wire 108 is in the process of
being advanced into a stylet port (not visible in FIG. 7) in an
intermediate portion 106 of lead 104. Stylet handle 102 includes a
first, longitudinal channel 112 and a second, longitudinal channel
110. Second longitudinal channel 110 may be seen to be disposed
within handles or wings 114. In some embodiments, the first
longitudinal channel 112 is dimensioned to firmly grasp and hold
lead 104 within.
[0034] FIG. 8 illustrates stylet handle 102 having stylet wire 108
held within first longitudinal channel 112. In some embodiments,
wings 114 can be squeezed together, as indicated at 116. This
squeezing motion can force apart the portions of handle 102 on
either side of first longitudinal channel 112, as indicated at 118,
thereby increasing the width of first longitudinal channel 112.
With the width slightly increased, stylet wire 108 can be more
easily transversely forced into first longitudinal channel 112, as
indicated at 120. In other embodiments, handle 102 is formed of
sufficiently elastic material to allow stylet wire 108 to be forced
into, and retrieved from, first channel 112 without squeezing on
the opposite side of the handle. In still another embodiment, the
stylet handle is formed from a substantially round cross-section,
cylindrical, elongate material, having the first, and second
channels formed on opposite sides of the elongated cylinder.
[0035] Handle 102 can be formed of a polymeric material, for
example, a thermoset plastic. In one embodiment, first longitudinal
channel 112 has about 0.050 inch width and about a 0.07 to 0.08
inch depth. Second longitudinal channel 110 can have a width of
about 0.2 inches and a depth of about 0.25 inches. The handle can
have a nominal width of about {fraction (3/5)}ths inch and a length
of 0.5 inch. In some embodiments, the handle is formed from a
{fraction (3/5)}ths inch outer diameter cylinder, and the channels
formed into opposite surfaces of the cylindrical piece.
[0036] In use, stylet wire 108 can be advanced into the insertion
port in lead 104 until the stylet wire is substantially totally
advanced into the lead. The lead can then be transversely forced
into the gripping first longitudinal channel, for example, by
squeezing opposing wings on the handle. The handle and the lead are
now aligned and move as a single unit. In particular, the handle
and lead now rotate together. The combined stylet and lead can now
be advanced into the introducer needle, as described below with
respect to the invention generally.
[0037] In use, an introducer needle, for example, a 14 or 16 gauge
Toughy needle, may be advanced into the intrathecal space in the
spinal column. The stylet may then be advanced distally through the
stylet opening to stiffen the lead. The now stiffened lead may be
advanced distally through the positioned introducer needle and into
the intrathecal space in the spinal column. The lead can be
advanced upward through the spinal canal, past the distal tip of
the introducer needle. When the lead has been properly positioned,
the stylet can be retracted from the lead, and the introducer
needle retracted from about the lead. The proximal region of the
lead, extending from the body, can be properly coupled to a lead
extension or directly to an implantable pulse generator. The free
end of the lead or lead extension can also be "tunneled" to an
appropriate site within the body for appropriate coupling to an
implantable pulse generator.
[0038] Referring again to FIG. 1, other aspects of the invention
may be further discussed. Inspection of FIG. 1 shows a length
between stylet opening 42 and distal end 30 as well as a length
between stylet opening 42 and proximal end 32. Different
applications and different target sites call for a different total
length for lead 20 between distal end 30 and proximal end 32.
Different treatments and target sites may also differ as to the
length of lead 20 to be inserted into the body.
[0039] In previous leads, leads having a different total length
required stylets or stiffening members having a corresponding
different length to match the lead length. The present invention
provides for a series of leads, each having a different total
length, but allowing for use of the same length stylet, provided
that the lead length between the stylet entrance and the distal end
of the stylet lumen is adapted to receive the same stylet. In one
example of the invention, a stylet having a length of about 15 cm
can be used with each member of a family of varying length leads
having a distance from stylet entrance to distal end of about 15
cm. This allows the treating physician to select the appropriate
lead while using the same stylet. As previously discussed, the
present invention also provides a design which can eliminate the
need for a lead extension, as the proximal portion can be quite
long.
[0040] The present invention can provide improved neurological
stimulation leads. This exemplary use of the present invention is
not limiting however. The present invention explicitly includes
implantable leads for both stimulation and sensing, and for
implantation in non-spinal sites, for example, brain and cardiac
implantation sites.
[0041] The foregoing detailed description should be read with
reference to the drawings, in which like elements in different
drawings are numbered identically. The drawings, which are not
necessarily to scale, depict selected embodiments and are not
intended to limit the scope of the invention. Several forms of
invention have been shown and described, and other forms will now
be apparent to those skilled in art. It will be understood that
embodiments shown in drawings and described above are merely for
illustrative purposes, and are not intended to limit scope of the
invention as defined in the claims which follow.
* * * * *